Students at Pennsylvania State were assigned to two groups. The first had to hug others at least 5 times a day over 4 weeks: front-to-front, non-sexual hugs using both arms. The others did not.
The huggers (averaging about 49 a week) became much happier
The guys who found it uncomfortable at first found ways to start, such as with success on the sports field
Later, the researchers found winking and complimenting also work
Happiness 1: hug
see: J M Clipman, 1999